package com.social.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.social.constant.RedisConstants.CACHE_BLANK_TTL;


@Component
public class CacheClient {

    private StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void  set(String key , Object value , Long time , TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    //设置逻辑过期时间
    public void  setWithLogicalExpire(String key , Object value , Long time , TimeUnit unit){
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));

        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    //解决缓存穿透
    public <R,ID> R queryWithPassThrough(
            String keyPrefix, ID id , Class<R> type , Function<ID, R> dbFallback,Long time , TimeUnit unit) {
        //1.从Redis里面查询缓存
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);

        //2.判断是否存在
        if(StrUtil.isNotBlank(json)) {
            //3.存在，直接返回
            return JSONUtil.toBean(json, type);
        }

        if(json != null){
            return null;
        }

        //4.不存在，根据id查询数据库
        R r = dbFallback.apply(id);
        //5.不存在返回错误
        if(r == null){
            stringRedisTemplate.opsForValue().set(key,"",CACHE_BLANK_TTL,TimeUnit.MINUTES);
            return null;
        }

        //6.存在，写入redis
        this.set(key,r,time,unit);

        return r;
    }


    private  static  final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    //逻辑过期
    public  <R ,ID> R queryWithLogicalExpire(
            String keyPrefix,ID id ,Class<R> type,String lockKeyPrefix,Function<ID,R> dbFallback,Long time , TimeUnit unit) {


        //1.从Redis里面查询缓存
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);

        //2.判断是否存在
        if(json == null) {
            return null;
        }

        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        R r = JSONUtil.toBean(data, type);
        LocalDateTime expireTime = redisData.getExpireTime();

        if(expireTime.isAfter(LocalDateTime.now())){

            return r;
        }

        String lockKey = lockKeyPrefix + id;

        boolean isLock = tryLock(lockKey);

        if(isLock){
            //开启新线程
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                try {
                    R r1 = dbFallback.apply(id);
                    this.setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    unLock(lockKey);
                }
            });
        }

        return r;
    }

    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.MINUTES);
        return BooleanUtil.isTrue(flag);
    }

    private boolean unLock(String key) {
        Boolean flag = stringRedisTemplate.delete(key);
        return BooleanUtil.isTrue(flag);
    }
}
